The first device on a PCI root bus determines whether the host bridge is
whitelisted for P2PDMA. All Intel Xeon chips since Ice Lake (ICX, 2021)
expose a device with ID 0x09a2 as first device. It is loosely associated
with the IOMMU. All these Xeon chips support P2PDMA, so since the addition
of the device with commit feaea1fe8b ("PCI/P2PDMA: Add Intel 3rd Gen
Intel Xeon Scalable Processors to whitelist"), P2PDMA has been allowed on
all new Xeons without the need to amend the whitelist:
Xeons with Performance Cores:
Sapphire Rapids (SPR, 2023)
Emerald Rapids (EMR, 2023)
Granite Rapids (GNR, 2024)
Diamond Rapids (DMR, 2026)
Xeons with Efficiency Cores:
Sierra Forest (SRF, 2024)
Clearwater Forest (CWF, 2026)
However these Xeons also expose accelerators as first device on a root bus
of its own:
QuickAssist Technology (QAT, crypto & compression accelerator)
Data Streaming Accelerator (DSA, dma engine)
In-Memory Analytics Accelerator (IAA, compression accelerator)
Whitelist them for P2PDMA as well. Move their Device ID macros from the
accelerator drivers to <linux/pci_ids.h> for reuse by P2PDMA code.
Unfortunately the Device IDs vary across Xeon generations as additional
features were added to the accelerators. This currently necessitates an
amendment for each new Xeon chip.
For future chips, this need shall be avoided by an ongoing effort to extend
ACPI HMAT with PCIe P2PDMA characteristics (latency, bandwidth, ordering
constraints). The PCI core will be able look up in this BIOS-provided ACPI
table whether P2PDMA is supported, instead of relying on a whitelist that
needs to be amended continuously.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Acked-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com> # QAT
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/6aac4922b5fe7070b11874427a9285e42ddd05a4.1780585518.git.lukas@wunner.de
0ba76b19fd